The radio frequency spectrum is a limited resource for which there is an ever-increasing demand from an expansive range of applications - all the way from commercial, such as mobile phones, to scientific, such as hurricane monitoring from space. Since radio waves do not stop at national borders, international regulation is necessary to ensure effective use of the radio spectrum for all parties. Use of the radio spectrum is regulated internationally by the Radio Regulations (RR), an international treaty. The International Telecommunication Union (ITU) has as its mission the facilitation of the efficient and interference-free use of the radio spectrum. Every 2 to 5 years, the ITU convenes a World Radiocommunication Conference (WRC) to review and revise the international RR. Changes to the RR are formulated through proposals to the conference according to Agenda Items, which are agreed on at the previous WRC. At the request of the National Science Foundation and the National Aeronautics and Space Administration, this report provides guidance to U.S. spectrum managers and policymakers as they prepare for the 2023 WRC to protect the scientific exploration of Earth and the universe using the radio spectrum. This report identifies the 2023 agenda items of relevance to U.S. radio astronomers and Earth remote sensing researchers, along with proposed agenda items for the 2027 WRC.